1. Field of the Invention
The field of the present invention is patient interface devices for use with opthalmic surgical laser systems.
2. Background
Many advances have been made in the area of ophthalmic surgery in recent years. In particular, lasers are being used more and more frequently to perform certain ophthalmic surgical procedures. One important aspect of such procedures is accurate positioning of the eye in relationship to the laser system, thereby allowing the laser beam to be directed with a high degree of accuracy. Accuracy in directing the laser beam during ophthalmic surgical procedures is important because an inaccurately or improperly directed laser beam could cause permanent damage to the eye.
One method of positioning the eye relative to the laser beam is to use a contact lens to stabilize the eye. This method, however, requires the contact lens itself to be accurately aligned with respect to the laser source, and therefore does not satisfactorily solve the alignment problem.
Another option for maintaining alignment between the eye and the laser source is to permanently mount the lens to the exit aperture of the laser system. However, with the contact lens permanently mounted on the laser system, the lens would require sterilization following each surgical procedure. Alternatively, the lens could be replaced following each procedure, but such an option introduces the need to align each replacement contact with the exit aperture before the system could be used. In either case, additional time and costs would be added to each procedure.
Alternative methods of providing accurate alignment are also known.] U.S. Pat. No. 5,549,632 to Lai, the disclosure of which is incorporated herein by reference, describes an apparatus for controlling the shape of the cornea during ophthalmic surgery. A transparent applanator plate is placed in contact with the cornea of a patient's eye. The applanator plate creates a fixed positional frame of reference which the laser beam control system can use to position the focus of the laser beam. A surgical tip at the distal end of an articulated arm having flexible joints is placed in contact with the applanator plate and follows any motion of the patient's eye and directs the laser beam to the surgical tip. The applanator plate also provides a means to control the contour of the index of refraction boundary between the corneal epithelium of the patient's eye and the air.
Various types of disposable contact lenses for use with ophthalmic laser systems are also known. For example, U.S. Pat. No. 6,254,595 to Juhasz et al., the disclosure of which is incorporated herein by reference, describes a disposable applanatic lens for use during ophthalmic laser surgery. The disposable applanatic lens includes a lens which has a flat anterior surface which is substantially parallel to a flat applanation surface. A skirt surrounds the applanation surface and extends outwardly therefrom to define a chamber. Additionally, the skirt includes a vacuum channel which is formed about the applanation surface. During procedures, contact between the skirt and the cornea encloses the vacuum channel. A vacuum pump is in fluid communication with the enclosed vacuum channel and is employed during the surgical procedure to at least partially evacuate the vacuum channel, thereby sealing the skirt against the cornea.
U.S. Pat. No. 6,373,571 to Juhasz et al., the disclosure of which is incorporated herein by reference, describes a disposable contact lens and an adjustable retainer ring for mounting the contact lens on the laser system. In order to properly align the disposable contact lens to the laser system, reference marks on the contact lens are brought into coincidence with predetermined focal points along the laser beam paths.